In the copending parent patent application Ser. No. 07/906,573, filed Jun. 30, 1992, assigned to the present assignee, small articles such as dry cell batteries, lipstick containers, lip balm containers and the like are labeled with high quality, thin film polymeric labels. Labels are fed to a label transport drum, which includes a fixed, cylindrically configured hub, and a cylindrically configured drum rotatably mounted on the hub. In the copending, parent patent application, the drum has an outer surface on which labels are fed as a strip, and moved with the drum through a label drag area on the drum surface where the label strip is cut into labels of predetermined size.
As the cut label moves with the rotating drum surface, an adhesive is applied by a rotary pad print head onto the area adjacent the leading edge of the label and a predetermined amount of solvent is evenly applied onto the area adjacent the trailing edge of the label. The solvent dissolves partially the solvent treated area, forming a tacky area which later provides a solvent-seal bond. The label moves to a label wrapping position where the articles, such as dry cell batteries, are wrapped, securing first the leading edge to the article, followed by overlapping the trailing edge onto the leading edge so that the trailing edge solvent creates a solvent-seal bond. The apparatus provides for high quality cylindrical labeling of small articles such as dry cell batteries using thin film, polymeric labels, e.g., typically less than 0.0035 inches thickness.
As disclosed in the copending, parent application, beneficial labeling results are obtained to the label with a rotating, flexible wiper tip which holds the solvent captive on the edge of the tip, and wrapping the article on a substantially smooth drum surface. In one disclosed embodiment of the invention, the wiper tip includes a V-notch for holding captive the solvent. As the wiper tip moves at the same surface speed as the label transport drum, the wiper tip is deflected against the trailing edge of the label. The solvent is evenly transferred to the label.
In another embodiment, a flexible, tapered tip evenly applies solvent onto the label when the surface speed of the wiper tip is different from the surface speed of the label and drum. In one embodiment, the speed differential between the wiper tip and the label causes application of a "bead" of solvent at the point of departure of the wiper from the label, at a point adjacent to, but spaced from the trailing edge of the label. If the wiper is moving slower than the surface speed of the label transport drum, the solvent is wiped toward the trailing edge of the label. If the wiper is moving faster than the surface speed of the label transport drum, the solvent is wiped from the trailing edge forward. As the article rolls back over the solvent during wrapping, the weight of the article pushes the solvent evenly across the pretreated area on which the solvent was applied onto the trailing edge, thus in essence obtaining a more even solvent wipe along the trailing edge of the label.
This high quality labeling of small articles, such as dry cell batteries, requires precision labeling at high operating speeds. At such high operating speeds, it has been found that it is sometimes difficult to transfer the leading edge onto an article without assisting the label transfer from the drum surface. Additionally, if an article misfeeds into the article wrapping position, the label should be retained onto the drum surface, and moved past the article wrapping position into a position where the label can be removed from the surface of the drum. This type of control is difficult to achieve, i.e., 1) transferring the label onto an article at an article wrapping position, or 2) retaining the label past the article wrapping position during article misfeed, and then removing the label from the drum surface.
There are some mechanical apparatus using forked arms which engage grooves in the drum surface to remove a label after an article misfeeds. However, the mechanical arms are inefficient and do not always perform adequately, especially at higher operating speeds. It is more desirable to use vacuum and pressure manifolds, ports and simple non-moving parts between the rotating drum and stationary hub to provide an efficient vacuum and pressure porting system on the label transport drum which 1) initially retains the label to the drum, 2) assists label transfer to an article at the label wrapping position, and 3) removes the label from the drum at a position past the article wrapping position if proper article wrapping has not occurred.